Method of and apparatus for gunfire control



Oct. 29, 1946. gROOKE 2,410,016

METHOD OF AND APPARATUS FOR GUNFIRE CONTROL Original Filed June 10, 19522 Sheets-Sheet l m 3 5 H Qw m E SUN 3. m m D Q N Y m B 3% A mm. um mew r3 3 Q Sq w Q t N, 3 i mw 8 3T m 5E mm m WQN Ir v n wm m \My .m2 8 M 2 .RE m2 5 E W o w c m.

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R mw mm 0 mm Q mm M 8 v Q g m Mw m 2 a MW %Q Oct; 29, 1946. R. E. CROOKEMETHOD OF AND APPARATUS FOR GUNFIRE CONTROL Original Filgd June 10, 19322 sh ts-sheet 2 :INVENTOR HAWOND E. 81200102 Patented Oct. 29, 1946METHOD or AND APPARATUS son GUNFIRE. CONTROL Raymond E. Crooke, NewYork, N. Y., assignor to Ford Instrument Company,

N. K, a corporation of City,

Application June Renewed '7 Claims. 1

This invention relates to a method of and apparatus for compensatingfor. errors in the aiming of ordnance mounted on angularly movableplatforms, such as ships.

The angular motions of a ship referred to herein are those relative to ahorizontal plane. They may be divided into two components hereinafterreferred to as level and cross-level. Level, designated L, is theinclination of the deck to the horizontal in the vertical plane of theline of sight. Cross-level, designated Z, is the inclination of the deckto the horizontal in a vertical plane 90 to the plane of the line ofsight.

As far as compensation for changes in the level angle is concerned, itmerely requires changes in elevation of the gun relative to the deck ofthe ship to maintain it at its proper elevation with respect to thehorizontal, corresponding to the range of the target, if the gun is tobe kept constantly in position to be fired at appropriate times, inother words, if the method of firing known as continuous aim is to beemployed.

As far as compensation for changes in crosslevel angle is concerned, amore serious problem arises for such movement causes a proportional tiltof the trunnions of the gun relative to the horizontal. This tilt, inconnection with the elevation of the gun, causes a displacement of thebore axis of the gun from the position it should occupy when the gun isproperly aimed. This displacement has a component in train and anotherone in elevation, the former being relatively large compared to thelatter. Since thecomponent in train depends upon the tangent of theangle of gun elevation, the error in train increases rapidly as theelevation of the gun is increased for long ranges.

In systems heretofore employed for applying cross-levelling correctionsto guns, the required corrections in train and elevation arecontinuously determined and appliedto the gun, with the result that thegun must be constantly shifted in train and elevation in accordance withthe changes in the cross-level angle of the ship. In the case of largecaliber guns which are normally fired at relatively high elevationangles, the introduction of the necessary correctional component intrain of the guns to compensate for trunnion tilt errors involvesconsiderable difiiculty on account of the magnitude of such component;for, as explained above, this component depends upon the tangent of theangle of elevation of the gun. The difliculty of rapidly moving somassive a body through large amplitudes is obvious.

It is an object of this invention to provide a Ind, Long Island New York1932, Serial No. 616,401 June 12, 1934 method of compensating for theerrors caused by the trunnion tilt of a gun, which avoids the abovementioned difficulties. An important advantage of the invention is thefact that it dispenses with the adjustment of the gun in train throughthe large amplitudes inherent in the requirements of the long rangeguns.

In brief, the method consists in firing only on a selected point in thecross-level and disregarding trunnion tilt errors for all othercross-level conditions, thereby avoiding the continuous adjustment ofthe train angle of the gun which would be necessitated if the gun wereto be kept continuously in the proper vertical plane. This isaccomplished by determining the corrections for the selected value ofthe cross-level of the gun, setting the gun with respect to the ship inaccordance with the determined corrections and firing the gun when themovement or the ship in cross-level brings the bore axisof the gun intoa vertical plane bearing a predetermined relation 'to the target atwhich the gun is aimed, this predetermined relation taking care of theother correctional factors such as time of flight and drift of theprojectile, the eifect of wind and the like.

It will be understood that in order for the gun to be properly aimedwhen it is brought into the specified vertical plane, its elevation withrespect to the deck of the ship must be continuously changed inaccordance with changes in the level angle. In general, the problem ofaccurately and rapidly changing the elevation of a gun is a less seriousone than moving it in train, and hence the fact that this inventionrequires that the a elevation of the gun be continuously changed tocompensate for changes in level angle is relatively of littleconsequence.

The invention also comprehends a suitable apparatus for carrying out themethod as above explained, and one form of such apparatus is hereinillustrated and will be hereinafter described. The particular nature ofthe invention, as Well as other objects and advantages thereof, willappear most clearly from the description of the particular apparatusillustrated in the drawings in which Fig. 1 is a simplified diagram ofone form of the appratus in which the invention may be embodied;

Fig. 2 is a corresponding diagram of certain elements of Fig. 1 in thepositions they occupy at a subsequent stage of operation.

In Fig. 1, D indicates in general a director having associated therewitha computer C for determining the correctional factors to be applied to agun G controlled by the director.

Preliminary to describing the apparatus in detail, it will be explainedthat the computer is intended to solve the following equations, which inpractice give sufficiently accurate results for the purpose for whichthe invention is intended to be used:

In these equations Zs represents the selected value of cross-level angleZ at which the gun is tobe fired;

Dz represents the correction selected cross-level;

Ds represents the horizontal angle between the vertical plane of theline of sight and the vertical plane in which the gun is to be fired,which angle is due to relative motion between the ship and the targetduring the time of flight of the projectile, drift, wind ballistics andthe like;

Us represents the elevation of the gun in a vertical plane from ahorizontal plane as a plane of reference;

Up represents the correction in elevation due to the selected crosslevel at which the gun is to be fired;

K1 and K2 are constants due to trigonometric approximations used in theequations.

Referring now to Fig. 1, the director D includes a pedestal I fixed tothe ship and provided with an annular rack 2 within which a table 3 isrotatably mounted upon the pedestal. The table is provided with astandard 4 carrying a shaft 5 provided with handwheels 6 to be used bythe trainer of the director. Attached to the shaft 5 is a bevel gear Iengaging a bevel gear 8 on the end of a shaft ll supported in thestandard 4 and carrying at its lower end a pinion Ill engaging with therack 2. A bevel gear I l likewise engages the bevel gear I and isattached to a shaft l?! which, by means of a pair of bevel gears l3,drives a shaft [4 which is connected to the side l5 of a differentiall5, the other elements of which will be hereinafter described.

Another standard [6 is also attached to the table 3 and carries a shaftI! provided with a pair of handwheels Hi to be used by the pointer. Theshaft 11 carries a bevelgear l9 meshing with a bevel gear 2B on thelower end of a shaft H. The upper end, of the shaft is connected by apair of bevel gears 22 to a shaft 23 which, by means of a pair of bevelgears 24; is connected to a shaft 25 provided with a worm 26 engaging agear sector 21 On a shaft 28 mounted in a standard 29 attached to thetable 3. The shaft 28 carries at one end a trainers telescope 30 and atthe otherv end a pointers telescope 3|.

A standard 32. is attached to the table 3 and carries a shaft 33v towhich is attached a pair of handwheels 34 for use by the operatorcommonly known as the cross-leveller. One of. the handwheels is providedwith a firing key 35 to be used by this operator. The shaft 33 alsocarries a bevel gear 36 engaging a bevel gear 31 on the end of a shaft38 which is connected by a pair of bevel gears 39 to a shaft 40. Thisshaft is provided with a worm 4| engaging a gear sector 42 on a shaft 43mounted at the upper end of a standard-44 attached to the table 3. Theother end of shaft 43 carries a cross-levellers telescope in train clueto the.

45 disposed at right angles to the directors and pointers telescopes 30and 3| respectively.

This telescope is intended to be set by the cross-leveller in accordancewith the selected value of cross-level Z at which the gun is to befired. It is shown in dot and dash lines in a horizontal position and infull lines in the position it occupies when set for the selected valueof cross-level.

The shaft 46 extends beyond the worm 4i into the computer of theinstrument. Bevel gears 43 connect this shaftto a shaft 41 connected bya pair of bevel. gears 48 to a shaft 49. By means of a pair of bevelgears 50, shaft 5| and a pinion 52, movement in accordance with thequantity KiZ is imparted to the slide 53 of a multiplying device,designated M for computing the crosslevel correction in train undervarious conditions of operation. The constant K1 is introduced by asuitable gear ratio. A link 54 provided with a pair of slots is pivotedto the slide 53. The shorter slot receives a fixed pin 55 and. thelonger slot receives a pin (not shown)- on the lower side of a carriage56 slidably mounted on one arm of a rectangular slide 57. The other armof this slide carries a pin 58 entering a spiral groove 59 on a gear 60adapted to be rotated in accordance with the factor U as will now bedescribed.

The groove is arranged to cause radial movements of the pin 58 inaccordance with the factor tan U A crank Bl on. the end of a shaft 62 isadapted to be set in accordance with the values of U received from anysuitable source. By means of a pair of bevel gears 63 the movement ofshaft 62 is imparted to a shaft 64 carrying a dial 65 reading against anindex 66 for showing the values of U applied to the computer. The shaft62 is-connected by a pair of bevel gears 61 to a shaft 68 carrying atone end a pinion G3 meshing with the gear 60.

Carriage 55 of the multiplying device M carries a pin I5 passing througha slot in the end of a slide H- which, therefore, receives a movementproportional to K12 tan U The slide 'H is provided with a rack whichengages a pinion "on a shaft 13 connected to the center 14 of adifferential '14, the center thus receiving a movement proportional toKiZ. tan U or D Gne side 14 of the differential is connected by means ofa pair of bevel gears 15 to a shaft i6 provided with a crank 11 by whichdeflection, Ds, may be applied to the computer. By means of a pair ofbevel gears 18 and shaft 19, the defiection thus applied is indicated bya dial reading against an index 8 I.

Since, as above explained, the center 14' of differential 14, receives amovement proportional to K12 tan U or D and the side 74" receives amovement proportional to D the side 14" will receive a movementproportional to the sum of these factors, i. e. D -kD or D The side 14"of the differential is connected to the side i5" of differential I5;Since the side 15 of this differential is connected to shaft M which ismovable in accordance with director train, the center l5' is movable inaccordance with the sum of the director train and D A shaft 82 isattached to the center IE' and actuates the rotatable element of a guntrain transmitter 83 in accordance with the movement of the center ofthe differential.

Side 14 of differential 14 engages a gear 84 on the end of a shaft 85which, through a pair of. bevel gearsBii.5 isconnected to the center 81'of a differential 81. The side 81" of the differential is driven throughgears from the shaft I6 which represents the D input. The other side 81"of the differential is connected by gears to a, shaft 88 which through apair of bevel gears 89 drives a shaft 89' having a pinion 90 engaging arectangular slide 9I of a multiplying device M for computing therequired cross-levelling correction in elevation, i. e. U

Since the center 81' of difierential 81 receives a movement from theside 14'' of differential I4 proportional to D +D and the side 81"receives a movement proportional to D from the shaft I6 the other side81 will receive a movement proportional to 2D +D of Equation 3, whichwill be imparted to slide 9 I.

The other arm of slide 9| carriesa slidable carriage 92 provided with apin (not shown) extending into one slot of a link 93, the other slot ofthis link being connected to a fixed pin 94. The other end of link 93 ispivotally connectedto a slide 95 provided with a-rack engaging a pinion96 on the end of a shaft 91 connected by a pair of bevel gears 98 to theend of shaft 49. The slide 95, therefore, receives a movementproportional to K2Z the constant being introduced by a suitable gearratio.

The carriage 92 carries a second pin 99 entering a slotted arm of aslide I00, the other arm of which is provided with a rack engaging apinion I M which receives a movement proportional to KzZ (2D +D which,according to Equation 3, is the required cross-levelling correction inelevation due to the selected value of cross-level Z I The pinion I M isattached to one end of a shaft I02 which, through a pair of bevel gearsI03, shaft I04 and bevel gears I05, drives the side I06 of adifferential I06, the center I06" of which is connected to the other endof shaft 68, which, as previously explained, is actuated in accordancewith the quantity U which is the elevation of the gun for the particularrange of the target. The other side I 06" is, therefore, movable inaccordance with the sum of the quantities U and U It carries a gear I01,which engages with a gear I08, connected to one side I09 of adifferential I09. The other side I09 of the differential is connectedthrough a pair of gears IIO, shaft III and a pair of bevel gears I L2 tothe shaft 23 which is rotated in accordance with changes in the levelangle L when the pointers telescope 3| is maintained on the target inelevation as it is in the operation of the system. This means that theside I09" of differential I09 receives a movement proportional to thelevel angle L and since the side I09 receives a movement proportional toU -I-U the center I09 is moved in accordance with the sum of thesequantities. The shaft II3 connected to the center I09 of thedifferential actuates the rotatable element of a gun elevationtransmitter I I4.

The gun indicated generally by G is shown in simplified form. Itconsists of a fixed rack II5 forming part of the gun mount and withinwhich is a rotatable turn table II6 provided with standards II'I bearingthe trunnions II 3 of the gun itself I I9.

The gun train transmitter 83 is electrically connected to one element ofa gun train receiver I20 of any suitable construction and which is notshown in detail since it forms no part of the present invention. As iscustomary in devices of this character, the other element of thereceiver is connected by a shaft I2I and pinion I22 to'the rack II5, thearrangement being such that when the gun is properly trained inaccordance with the value transmitted by gun train transmitter 83, asuitable indication to that effect will be given by the receiver in awell known manner.

A similar type of gun elevation receiver I23 is employed, one elementbeing electrically connected to the gun elevation transmitter H4 and theother element to a trunnion of the gun so that when the gun is properlyelevated in accordance with the value transmitted from the gun elevationtransmitter this fact will be indicated by the receiver.

In Fig. 1 the gun is shown in dot and dash lines in the position itoccupies when the platform is horizontal and the gun is aimed at thetarget, assuming no deflection for the purpose of simplicity. Thisposition corresponds to the dot and dash line position of telescope 45.The gun train and gun elevation receivers are shown in theircorresponding positions. Under these circumstances the bore axis of thegun, indicated by the line AA, lies substantially in the vertical planeof the line of sight, neglecting any corrections for parallax due todifferences in the positions on the ship of the director and the gun.

In Fig. 1 the full line positions of the gun and its train and elevationreceivers, represent the conditions of these elements when thecorrectional factors corresponding to those required for the particularvalue of cross-level at which it is desired to fire the gun, have beencomputed. and applied to the gun in the following manner:

In the operation of the apparatus the trainer by manipulation of hishandwheel 6 connected to the pinion I0, keeps his telescope 30 on thetarget. andthereby transmits director train through shaft I4 to the sideI5 of differential I5.

As explained above, the system is operated in accordance with continuousaim, which means that the pointer likewise keeps his telescope 3| on thetarget, in spite of changes in level angle, L, by manipulation of hishandwheels I8, and the connections therefrom to the shaft 28 whichcarries the telescope. This movement is also imparted by shaft 23 to theside I 09" of the differential I09.

As far as the cross-leveller is concerned, he sets his telescope 45 atthe selected value Z of the cross-level at which it is desired to firethe gun. The position of the telescope under this condition is shown infull line. This operation through the connections leading from shaft 40,positions the slides 53 and of the multipliers M and M respectively, inaccordance with the selected cross-level to introduce this factor forcomputing the required cross-levelling corrections in train andelevation.

A fourth operator sets in, by means of crank GI, the values of gunelevation, U thereby adjusting the gear 60 with its tangent cam groove.This action correspondingl adjusts the center I06" of the differentialI06.

Under the assumed conditions of no deflection, the crank 11 remains atits normal position so that the side 14" of the differential I4 may beregarded as fixed. As previously described, the multiplying device Mgenerates the value of D for the selected value of cross-level at whichthe gun is to be fired. This factor is combined with deflection, whenthe latter is present, in the differential 14. The center Id of thedifferential is actuated in accordance with D The side 74" transmitsthis quantity to the side I5! of differential l5, where it is combinedwith director train as imparted to the side l of the differential by theshaft M. The center of this differential, therefore, actuates the guntrain transmitter with the result that when the gun is correspondinglytrained it assumes the position shown in full lines.

As previously described, the multiplying device M computes thecross-levelling correction in elevation, U corresponding to the selectedvalue of the cross-level. The result of this computation is transmittedfrom the. pinion IOI to the side I06 of differential I06 where it iscombined with the gun elevation representedby U so that the side IUB ofthe differential transmits the sum of these quantities to the side I09of differential I09. Side I09" receives,.as previously explained, amovement equal to the level angle L, so that the required gun. elevationis transmitted to the gun to correspondingly position it in elevation aslikewise shown by its full line position.

It will be apparent, from the above description and assuming that theship is on even keel so far as cross-level is concerned, that the gunwill be displaced both in train and elevation to a position where itwill not be aimed at the target, in spite of the fact that the pointerand the trainer are sighting on the target. As. angular movement of theship in cross-level takes place, the cross-leveller notes the passage ofthe cross wires of his telescope 45 across the horizon, which means thatat this instant the angular position of the ship corresponds to theselected value of cross-level at which the gun is to be fired. Thisangular movement of the ship will turn the gun mount through acorresponding angle, so that, as shown most clearly in Fig. 2, the boreaxis A-A of the gun is now in the vertical plane of the line of sightand in proper position to be fired by the cross-leveller actuating hisfiring key.

While a preferred embodiment of the invention has been shown anddescribed, it will be understood that the invention may be embodied inother forms and various changes may be made in structural detailswithout departing from its principle as defined in the appended claims;

I claim:

1. The method of correcting for the effect of trunnion tilt of a gunmounted on an angularly movable platform which consists in determiningthe correction for the gun for a selected value of cross-level otherthan zero, setting the gun with respect to the platform in accordancewith the determined correction and firing the gun when the movement ofthe platform brings the gun into a vertical plane bearing apredetermined relation to the target at which the gun is'aimed.

2. The method of correcting for the effect of trunnion tiltof a gunmounted on anangularly movable platform which consists in determiningthe correction for the gun for a selected value of cross-level otherthan zero, setting the gun with respect to the platform in accordancewith the determined correction and firing the gun when the platformpartakes of a cross-level equal to that for which the correction wasdetermined.

3. The method of correcting for the effect of trunnion tilt of a gunmounted on an angularly movable platform which consists in determiningthe correction in train for the gun for a selected value of cross-levelother than zero, setting the gun in train with respect to the platformin accordance with the determined correction and firing the gum when themovement of the platform brings the gun into a vertical plane bearing apredetermined relation to the target at which the gun is aimed.

l. The method of correcting for the effect of trunnion tilt of a gunmounted on an angularly movable platform which consists in determiningthe correction in train for the gun for a selected value of cross-levelother than zero, setting the gun in train with respect to the platformin accordance with the determined correction and firing the gun when.the platform partakes of a cross-level equal to that for which thecorrection was determined.

5. The method of aiming and firing a gun mounted on an angularly movableplatform which consists in maintaining aline of sight from the platformto a target, maintaining the gun in a predetermined relation to saidline ofsight throughout relative movement between the target and theplatform in a vertical plane containing the line of sight, establishinga second line of sight bearing a predetermined vertical angular relationto a horizontal plane and lying in a vertical plane bearing apredetermined angular relation to the first named vertical plane,generating thecorrections necessary to compensate for errors in th aimof the gun due to the tilt of the trunnions of the gun resulting fromangular. movement of the platform measured in the second mentionedvertical plane equal to said predetermined vertical angular relation ofthe second line of sight, positioning the gun relatively to the platformin accordance with said generated corrections and firing the gun whenthe'second line of sight is brought horizontal by said angular movementof the platform.

6. The method of aimin and firing a gun mounted on an angularly movableplatform which consists in establishing a line of sight from theplatformto the target in a vertical plane through the target,establishing a second line of sight bearing a predetermined verticalangular relation to a horizontal plane and lying in avertical planebearing a predetermined angular relation to the first named verticalplane, generating the corrections for the tilt of the trunnions of thegun which corrections correspond to those required for angular movementof the platform measured in the second named vertical plane equal tosaid predetermined vertical angular relation of the second line ofsight, positioning the gun relatively to the platform in accordance withsaid generated corrections and firing the gun when the second line ofsight is brought horizontal by said angular movement of the platform.

'7. The method of aiming and firing a gun mounted on an angularlymovable platform, which consists in compensating for the effect upon thegun of angular movement of the platform in the vertical plane ofthe-line of sight to the target, determining the corrections in the aimof the gun resulting from trunnion tilt of the gun caused by selectedangular movement of the platform in a vertical planesubstantiallyperpendicular to the first named plane, adjusting the gun with respectto the platform in accordance with the determined trunnion tiltcorrections and firing the gun when the platform partakes of an angularmovement in the second named vertical plane equal to that for which thcorrection was determined.

RAYMOND E. CROOKE.

